Antioxidant Potential and Bioactive Profiles of Non-Edible Parts of Araucaria angustifolia: Comparative Extraction Methods and Oxidative Stability Evaluation.

Abstract

This study explores the antioxidant potential of Araucaria angustifolia, a native Brazilian conifer, focusing on its non-edible parts: trunk bark, seed coat, and spikes. Aqueous, methanolic, and acetonic extracts were prepared and analyzed for antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC) assays, along with their phenolic compound composition. Methanolic extracts exhibited the strongest antioxidant activity and the highest total phenolic content. Key bioactive compounds identified included gallic acid, 4-hydroxybenzoic acid, caffeic acid, chlorogenic acid, quercetin, and myricetin, with the trunk bark methanolic extract showing the highest concentrations of these compounds. In oxidative stability tests using food matrices, such as homemade buttermilk and soybean oil, the trunk bark methanolic extract extended the induction point to 19:06 h, demonstrating its effectiveness in delaying lipid oxidation. UV-Vis spectroscopy confirmed the presence of bioactive compounds and revealed distinct absorption profiles for each solvent. Principal component analysis further distinguished methanolic extracts for their enrichment in phenolics and flavonoids compared to aqueous and acetonic extracts. The antioxidant capacity of Araucaria angustifolia was comparable to that of other coniferous species, such as pine, reinforcing its potential as a natural source of antioxidants. Methanol proved to be the most effective solvent for extracting bioactive compounds. These findings highlight the potential of Araucaria angustifolia extracts for applications in food preservation, nutraceuticals, pharmaceuticals, and cosmetics, emphasizing the value of its non-edible parts as sustainable sources of natural antioxidants.